I was thinking and came up with this. I know it's wrong but can't find the mistake :((adsbygoogle = window.adsbygoogle || []).push({});

dy/dx sin(x) = cos(x)

dy/dx sin(kx) = kcos(kx)

So dy/dx sin(3x) = 3cos(3x)

Now let Y = 3x

dy/dx sin(Y) = cos(Y) = cos(3x)

3cos(3x) = cos(3x)

3 = 1

Where is the mistake?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Differentiation of sin function where's my mistake?

Have something to add?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**